[jpelosi2002]

I bought all my components to make a power supply like 2 years ago. At the time i was planning on buying a much bigger mill. Well I wound up with a little X2 mini mill. My power supply is putting out around 55 VDC after the capacitor. I would like it to be around 35 VDC for use with a Keling 4030 stepper driver.
Here's my specs:
Transformer: Avel Lindberg 500 VA 35V + 35V
Capacitor: Mallory 25,000 uf 75 VDC.

Im only using "half" of the transformer and I'm still getting 43 VDC after the bridge rectifier, and again, 55 VDC after the cap.
My target is around 35 VDC at like 3 amps.
Any help would be appreciated. I'm in over my head here.
Jim

[Al_The_Man]

It looks like you may have 35-0-35 centre tap winding or do you have two separate 35v secondaries?
Either way, I would look at taking turns off, if C.T. winding you just need to reduce one of secondaries, this will still give you 20amps at 24vac.
The current capacity will be governed by the wire dia as well as the VA.
to reduce around 11vac you will most likely need around 22 turns off.
Al.

[Zig]

If You do not mind a bit of complexity .. you might consider interposing a phase controlled rectifier ( an SCR ) inbetween the filter capacitor and bridge rectifier.

Might be easier than removing windings from the secondary.A kind of an oldfashioned preregulator approach.